Java编写时间工具类ZTDateTimeUtil的示例代码

 Date date = new Date();
 SimpleDateFormat simpleDateFormat = new SimpleDateFormat("yyyy-MM-dd");
 String datestring  = simpleDateFormat.format(date);
 System.out.printf(datestring);

public  static String TimeFormat ="yyyy-MM-dd";
    public static void main(String[] args) {
        Date date =new Date(System.currentTimeMillis());
        SimpleDateFormat simpleDateFormat = new SimpleDateFormat(TimeFormat);
        String dateformat=simpleDateFormat.format(date);
        System.out.printf(dateformat);
        Date dateafterFormat =null;
        try {
            dateafterFormat=simpleDateFormat.parse(dateformat);
            System.out.printf(String.valueOf(dateafterFormat));
        } catch (ParseException e) {
            throw new RuntimeException(e);
        }
    }

//parse(String text, ParsePosition pos)
//解析字符串中的文本以Date生成,parase需要背用try-catch包围
 String dateTime ="2023-01-16 17:35:16";
  SimpleDateFormat simpleDateFormat = new SimpleDateFormat("yyyy-MM-dd");
    try {
        Date date =simpleDateFormat.parse(dateTime);
        System.out.printf(date.toString());
    } catch (ParseException e) {
        throw new RuntimeException(e);
}

 //时间相等返回0，time1大于time2返回1，time1小于time2返回-1
  Date time1 = new Date(System.currentTimeMillis());
  String date ="2023-01-17 17:35:16";
   Date time2 = null;
   try {
       time2 = new SimpleDateFormat("yyyy-MM-dd").parse(date);
   } catch (ParseException e) {
       throw new RuntimeException(e);
   }
   int flag =time1.compareTo(time2);
   System.out.printf(flag+"");

 public static String date2Str(Date date, String format) {
        if (null == date) {
            return null;
        }
        SimpleDateFormat sdf = new SimpleDateFormat(format);
        return sdf.format(date);
}

public static String changesStringTimestamToformat(String timestamp){
        LocalDateTime parse = LocalDateTime.ofInstant(Instant.ofEpochMilli(Long.parseLong(timestamp)), ZoneId.systemDefault());
        String format = parse.format(DateTimeFormatter.ofPattern("yyyy-MM-dd hh:mm:ss"));
        return format;
    }

package com.awifi.cloudnative.container.rbac.user.provider.utils;

import java.text.DateFormat;
import java.text.SimpleDateFormat;
import java.util.Calendar;
import java.util.Date;

/**
* @Author 张鑫
* @Date 2022/4/20
* @Param 
* @return 
**/
public class dataFormatUtils {
   
   
   /**
    * 时间格式化
    *
    * @param date
    * @return
    */
   public static String format(Date date) {
       // 计算出相差天数
       int days = differentDays(date, new Date());
       // 同一天
       if (0 == days) {
           // 计算出时间差
           long delta = new Date().getTime() - date.getTime();
           // 小于一分钟
           if (delta < 1L * 60000L) {
               long seconds = toSeconds(delta);
               return (seconds <= 0 ? 1 : seconds) + "秒前";
           }
           // 小于一小时
           else if (delta < 1L * 3600000L) {
               long minutes = toMinutes(delta);
               return (minutes <= 0 ? 1 : minutes) + "分钟前";
           }
           // 小于24小时
           else if (delta < 24L * 3600000L) {
               long hours = toHours(delta);
               return (hours <= 0 ? 1 : hours) + "小时前";
           }
       }
       // 不同一天
       else {
           if (1 == days) {
               return "昨天";
           }
           // 几天前
           else if (3 >= days) {
               return days + "天前";
           }
       }
       // 格式化时间
       return getYmdHm(date);
   }

   /**
    * 获取秒
    *
    * @param date
    * @return
    */
   private static long toSeconds(long date) {
       return date / 1000L;
   }

   /**
    * 获取分钟
    *
    * @param date
    * @return
    */
   private static long toMinutes(long date) {
       return toSeconds(date) / 60L;
   }

   /**
    * 获取小时
    *
    * @param date
    * @return
    */
   private static long toHours(long date) {
       return toMinutes(date) / 60L;
   }

   /**
    * 时间格式化，yyyy-MM-dd HH:mm
    */
   public static String getYmdHm(Date date) {
       DateFormat df = new SimpleDateFormat("yyyy-MM-dd HH:mm");
       return df.format(date);
   }

   /**
    * 获取天数
    *
    * @param oldDate
    * @param newDate
    * @return
    */
   public static int differentDays(Date oldDate, Date newDate) {
       Calendar oldCal = Calendar.getInstance();
       oldCal.setTime(oldDate);

       Calendar newCal = Calendar.getInstance();
       newCal.setTime(newDate);
       int oldDay = oldCal.get(Calendar.DAY_OF_YEAR);
       int newDay = newCal.get(Calendar.DAY_OF_YEAR);

       int oldYear = oldCal.get(Calendar.YEAR);
       int newYear = newCal.get(Calendar.YEAR);
       // 不是同一年
       if (oldYear != newYear) {
           int timeDistance = 0;
           for (int i = oldYear; i < newYear; i++) {
               //如果是闰年
               if (i % 4 == 0 && i % 100 != 0 || i % 400 == 0) {
                   timeDistance += 366;
               }
               //不是闰年
               else {
                   timeDistance += 365;
               }
           }
           return timeDistance + (newDay - oldDay);
       }
       // 是同一年
       else {
           return newDay - oldDay;
       }
   }
}